Mechanical Engineering Commons^™

External Force Control Of Transitional And Turbulent Flows, Cesar Alberto Leos

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Turbulence in wall-bounded flows governs momentum transport, drag, and energy efficiency in a wide range of engineering systems, yet its response to external forcing remains incompletely understood across transitional and high Reynolds number regimes. This dissertation investigates an active flow control strategy based on spanwise external forcing and demonstrates how it modifies the dynamics of transitional and turbulent channel flows with the objective of identifying the mechanisms through which forcing alters transition, flow physics, and turbulent drag reduction.

Firstly, direct numerical simulations are performed to examine the subcritical transition under external forcing. The onset and sustenance of turbulence are shown …

Vacuum Modification Of The Surface Properties Of T15k6 Hard Alloy By Plasma–Chemical Synthesis Of Tin-Cu Coatings, Aleksandr Semenov, Dmitriy Tsyrenov, Nikolay Ulakhanov, Irina Semenova, Undrakh Mishigdorzhiyn, Wen Ma, Simon C. Tung, George E. Totten

Mechanical and Materials Engineering Faculty Publications and Presentations

The design and main parameters of a plasma–chemical reactor containing two compartments are presented. One compartment houses a vacuum-arc evaporator, while the other houses a planar magnetron. The compartments are separated by a diaphragm with a dosing slot for injecting copper vapor into the TiN synthesis compartment. The conditions for the synthesis of superhard TiN-Cu composite coatings are experimentally determined. Based on established process parameters for TiN synthesis in a nitrogen-containing plasma by Ti evaporation using a vacuum-arc discharge, it is proposed to apply TiN-Cu coatings by injecting Cu vapor into the TiN synthesis area and sputtering Cu using a …

Lockheed Martin & U.S. Navy Air Pallet For Materials Handling, Samantha Ryan, Ryan Zerneke, Joshua Bible, Justin Conner, Brycen Haner, Nevan Juteram, Alexander Lacy, Gavin Lanka, Henry Lewis

Mechanical and Civil Engineering Student Publications

The purpose of this project is to design, manufacture, and deliver an Air Pallet capable of lifting heavy loads and positively engaging with the Drive Tractor for movement. This project was developed to address current maintenance hazards and difficulty, structural integrity concerns, and increase system reliability for our customers Lockheed Martin and the United States Navy.

3d Filament Recycler, Connor Easley, Stephan Jean-Baptiste, Armando Loynaz, Brody Paulk, Meagan Prouty, Tai Roberts, Jack Salcedo, Vanessa Tohorton, Alex Tremblay, Ruhaan Zaveri

Mechanical and Civil Engineering Student Publications

The purpose of the project is to design and manufacture an integrated system for the L3HSDC that can recycle 3D filament waste by shredding, heating, extruding, and spooling it.

The Matear System, Kylie Strong, Adel Siraeva, Julianna Bartus, Lilly Davies, Cameron Deen, Rayna Doty, Amiana Mata, Jack Minners, Matthew Skwiot

Mechanical and Civil Engineering Student Publications

The MATEAR attachment collects regolith simulant and uses compression and heat to form brick-like building blocks for sustainable infrastructure. It mounts to the Clearpath Robotics Husky A200 rover provided by the team’s faculty advisor.

Lockheed Martin & U.S. Navy Drive Tractor, Nicolas Czincila, Andrew Pestone, Santiago Florez-Tascon, Kalvin Long, Nick Norman, Joseph Phan, Ashlynn Redding, Brandon Ribeiro, Noah Rodriguez, Diana Viherek, Mckenzie Winder

Mechanical and Civil Engineering Student Publications

The purpose of this project is to design and manufacture a manually operated, pneumatic-assisted Drive Tractor system for transporting heavy loads with the Air Pallet. This project was developed to improve maneuverability, reduce operator effort, and increase system reliability within industrial environments for our customers Lockheed Martin and the U.S Navy.

Sparcc – Solar Panel Augmentation Via Regulated Cooling And Cleaning, Zachary Rodgers, Connor Fromme, Mohammed Al Jahwari, Jack Connor, Nicolas Hubley, Adrian Kingdollar, Iain Leroy, Maria Jesus Munoz, Ashton Stringer

Mechanical and Civil Engineering Student Publications

Problem Statement: Solar energy is the fastest-growing source of energy in the world. Solar cells lose efficiency by 0.35-0.7% per degree Celsius and up to 98% from debris build up. The primary objective of SPARCC was to improve cell efficiency through cooling and cleaning. A brush system with water spray was implemented to clean the panels, and a passive cooling system that utilizes a solar chimney, heat sinks, and phase change material to clean and cool.

Automatic Determination Of Mechanical Properties From Molecular Dynamic Stress-Strain Curves Using Regression Fringe Response, Josh Kemppainen, Tristan Muzzy, Travis Wavrunek, Gregory Odegard

Michigan Tech Publications

Molecular dynamics (MD) simulations have become a powerful tool for studying polymers, designing new materials, and composites. Mechanical behavior in MD simulations are typically evaluated through stress-strain curves. However, MD-generated stress-strain curves are often obscured by thermal noise from atomic vibrations. This noise complicates the reliable derivation of mechanical properties and hinders objective and reproducible analysis. The noise in the stress-strain curves has been removed by using a Butterworth low-pass filter, enabling clearer interpretation of stress-strain data. Building on this, a novel analysis framework the Regression Fringe Response (RFR) is introduced to systematically determine the Young's modulus, yield strength, and …

Transitional And Turbulent Dynamics In Viscoelastic Wall-Bounded Flows, Alexia Martinez Ibarra

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The addition of small amounts of long-chain polymers to a turbulent flow has been reported to modify the flow phenomena when compared to Newtonian flows, resulting in a significant skin-friction reduction. Although polymer-induced drag reduction has been extensively studied through both experimental and numerical studies, a unified and predictive understanding of the phenomenon is still lacking. This dissertation focuses on better understanding of this phenomenon, particularly on the transitional regime, which remains largely unexplored but is of utmost importance for both practical and fundamental purposes.

Firstly, direct numerical simulations are performed to study the effect of polymers on the laminar-turbulent …

Cast In Steel: Horseman's Axe, Sam A. Morris

Create@State

Cast in Steel is a competition between universities across North America started by the Steel Founders Society of America. The competition is centered around giving students the opportunity to learn about casting and the steel industry in general. A prompt of a weapon or tool with some level of historical significance is given to all the teams. The prompt for the 2026 Arkansas State University team, was a Horseman’s Axe. The team designed their rendition of a horseman’s axe, worked with Southern Cast Products as their local industry parter, and fabricated a finished axe to represent Arkansas State University as …

Analysis For Predicting Surface Temperature And Combustion Of Heavy-Duty, Pre-Chamber-Enabled, Hydrogen Engines, Tony Spezia

Master's Theses (2009 -)

Hydrogen as an alternative fuel shows great promise to help reduce greenhouse gas emissions from heavy duty engines. However, the challenge for hydrogen engines is that hydrogen has very different combustion properties compared to conventional hydrocarbon fuels. Hydrogen has very high flame speeds, very low ignition energy, and very wide flammability limit. These properties result in hydrogen engines being prone to abnormal combustion. Abnormal combustion makes hydrogen engines difficult to control or can cause catastrophic damage to the engine, so it is important to avoid conditions where abnormal combustion occurs. Hot spots along the combustion chamber walls are often the …

Techno-Economic Analysis Of Hybrid Systems As A Solution For Electricity Supply During The Dry Season At The Bakaru Run-Of-River Hydropower Plant, Zamharir Aditya Febri, Mohammad Akita Indianto, Sheila Tobing

Journal of Materials Exploration and Findings

Within the South Sulawesi power system (Sulbagsel), the Bakaru Hydro Power Plant serves as a key facility expected to provide consistent and reliable electricity supply. However, since the Bakaru plant operates under a Run of River scheme, its energy output is highly dependent on river discharge rates. In 2024, a significant decrease in water flow was recorded between August and October, which led to a drastic reduction in power generation. To address this challenge, a hybrid energy system is proposed to ensure continuous load coverage, particularly during the dry season. The optimal configuration of this hybrid system was modeled and …

Techno-Enviro-Economic Analysis Of Precipitated Calcium Carbonate Production From Carbon Dioxide In Cement Industry Flue Gas And Calcium Hydroxide, Natalia Debora Panggabean, Widodo Wahyu Purwanto

Journal of Materials Exploration and Findings

CCUS is a technological solution to reduce emissions from the cement industry, which is the second largest CO2-intensive industry. This study aims to analyze technical, economic, and environmental performance of Precipitated Calcium Carbonate (PCC) synthesis in cement industry flue gas. The process simulation includes the CO2 capture system from cement plant, CO2 captured used as feedstock for PCC synthesis process through its reaction with calcium hydroxide. The simulation was carried out using ASPEN Plus software. Technical analysis was performed to determine the CO2 capture efficiency and PCC synthesis efficiency. Economic analysis was conducted to calculate CO2 capture cost and production …

Feasibility Analysis Of Thermal Oxidizer To Determine Remaining Life Using Fitness- For-Service Level 3 Method, Yudhi Yudistirawan, Donanta Dhaneswara, Wahyuaji Narottama Putra, Gama Widyaputra, Dewi Kurnia Suci, Agung Putra Mahardhika

Journal of Materials Exploration and Findings

An aged thermal oxidizer (TOX) in the oil and gas industry necessitates a comprehensive evaluation to ensure its continued safe operation. This study presents a Remaining Life Assessment (RLA) and a Fitness for Service (FFS) evaluation for the four main components of the TOX, in accordance with API 510, API 579/ASME FFS-1, and ASME BPVC Section VIII Div-1 standards. The investigation includes the determination of maximum stress and maximum temperature required to assess the operational viability of the reactor. The four components are radiant, convection, transition, and stack sections—were modeled using the finite element method (FEM). Following the geometric modeling, …

Risk Identification Of Green Hydrogen Supply Chain In Ammonia Industry In Indonesia Using Delphi And Topsis Methods, Ananda Priatama, Sheila Tobing

Journal of Materials Exploration and Findings

The development of green hydrogen in Indonesia, while promising for supporting industrial decarbonization, remains in its early stages and faces various challenges across technical, economic, and regulatory domains. This study aims to identify and prioritize the risks linked to green hydrogen supply chain in Indonesia, particularly for applications in the ammonia industry. A set of 49 potential risk factors was initially compiled through literature review and prior studies. The Delphi method was employed with a panel of experts to validate these risks, ultimately refining the list to 27 critical risk factors. Subsequently, the Technique for Order Preference by Similarity to …

A Sustainable Approach To Tensile Property Enhancement In Sand Casting Via Metal Chip–Sand Composite Molds, Maaruf Isyaku, Danjuma Saleh Yawas, Mathew Olatunde Afolayan, Terva Ause

Journal of Materials Exploration and Findings

The present work focuses on the study of the effect of adding different weight percentages and particle sizes of various metal chips to foundry sand on the tensile strength of aluminum alloy castings, utilizing Taguchi's optimization methodology and regression analysis. Characterization techniques such as X-ray fluorescence (XRF), thermogravimetry, and SEM were also used. The XRF analysis identified aluminum (76.61%), silicon (17.49%), and magnesium (1.28%) as the major elements in the aluminum alloy engine block. For the foundry sand, silicon (89.51%), phosphorus (7.41%), and potassium (1.7%) were found. In contrast, the major constituents in cast iron included iron (88.3%), carbon (3.7%), …

Assessing Passenger Electric Vehicle Growth Strategies And Their Impacts On Electricity Demand Load And Co2 Emissions In Aceh Province To Achieve Net Zero Emission Target By 2060, Taufik Hidayat, Widodo Wahyu Purwanto

Journal of Materials Exploration and Findings

The electrification of the transport sector is a crucial pathway for achieving Indonesia’s Net Zero Emissions (NZE) target by 2060. This study assesses the potential impact of passenger electric vehicle (EV) penetration on electricity demand and CO2 emissions in Aceh Province through a scenario-based modelling approach. Two policy-aligned scenarios are assessed: a low-penetration (LP) scenario and a high-penetration (HP) scenario. Using the Gompertz model and the ASIF framework, total CO2 emissions were projected from 2020 to 2060. Results show that although higher EV penetration reduces direct emissions from internal combustion engine (ICE) vehicles, total CO2 emissions increase more significantly under …

Leveraging Convolutional Neural Networks For Through-The-Wall Radar Imaging: Challenges, Impacts, And Future Directions, Tumaini Edgar, Abdulla F. Ally, Abdi T. Abdalla

Tanzania Journal of Engineering and Technology (TJET)

Through-the-wall radar imaging (TWRI) is an essential technology for military and rescue applications; however, its performance in detecting and visualizing high-quality images of targets behind walls is significantly degraded by multipath reflections and signal attenuation. This paper reviews the current state of TWRI and its challenges, and explores the transformative potential of deep learning, particularly convolutional neural networks (CNNs), in addressing these challenges. Peer-reviewed articles published from 2018 to 2024 were analysed to examine CNN applications in addressing TWRI challenges. The analysis reveals that using CNNs, TWRI systems can be more effective by filtering wall distortions, reducing noise, lowering computational …

A Review Of Energy Storage Technologies With Hydro Energy System Design For Off-Grid Electricity, Daniel H. Ngoma, Banet L. Masenga

Tanzania Journal of Engineering and Technology (TJET)

Many renewable energy sources such hydropower—particularly small-scale run-of-river and micro-hydro—offers reliable, low-cost generation. However, their inherent intermittency (due to seasonal flow variations) and inability to instantly match demand necessitate integrated energy storage to ensure a stable, continuous power supply. This review synthesizes contemporary energy storage technologies in the context of their integration with off-grid hydro energy system design.

The study examine a spectrum of storage solutions, evaluating their technical characteristics, costs, and suitability for hybrid hydro applications. Pumped Hydro Storage (PHS), while highly efficient and large-scale, is often geographically constrained and capital-intensive for small off-grid projects. Battery Energy Storage Systems …

Implementation Of The Fourth Industrial Revolution Technologies In Tanzania’S Downstream Oil And Gas Industries, Vitalis John Mwinyi

Tanzania Journal of Engineering and Technology (TJET)

The advent of the fourth industrial revolution (IR4.0) has resulted in the digital transformation of multiple sectors of the economy due to the disruptive nature of the technologies driving the revolution. The technologies have already found their way into the oil and gas industries across the globe, especially in upstream, midstream, and downstream operations. However, the degree of implementation is not the same for these operations, considering the complexities involved, integrated process, the associated risk and investment cost, among others. This study aimed to establish the implementation level of IR4.0 technologies in the downstream operations. A survey method was employed …